1. Field Of The Invention
This invention relates to high-intensity arc lamps, and more particularly, to the dissipation of heat generated by short-arc, gaseous-discharge lamps operating at high temperatures and pressures. The light of the present invention incorporates such a high intensity arc lamp in a light which is motion controlled to pivot about two axes.
2. Description Of The Prior Art
As it is known in the art, a short-arc discharge lamp generally includes an anode electrode and a cathode electrode located within a sealed quartz envelope containing a gas, such as xenon, mercury, krypton, etc., and is maintained under high pressure in the order of about 20 atmospheres. The anode and cathode electrodes are aligned axially in the envelope with their tips spaced apart by a predetermined distance to conduct current upon application of high voltage pulses and produce an intense arc emitting a continuous spectrum of useful light. Thus, the short-arc, high-intensity lamp has been used as an excellent source of concentrated white light for searchlights, spotlights and the like. In most applications, for good performance, an auxiliary lens or mirror has been used to direct emitted light in a concentrated beam. The light source is generally positioned at a focal point of the accompanying reflecting mirror, and the surface of the mirror is maintained free of dust by enclosing it within a sealed housing.
With ever-increasing demand for short-arc lamps of the aforedescribed type, their capacity as a source for high intensity light has often been stretched beyond the design limits with the resulting detrimental effect of shortening the life of the lamp. U.S. Pat. No. 3,684,908, issued to N. C. Beese, discloses such an arc lamp with a parabolic reflector shell having a plurality of external air ducts through which air is forced to cool the heated lamp. The ducts extend radially from a central, tubular neck of a reflector shell toward an outer rim to provide passages for removing heat from the lamp through the reflector shell. An exterior surface of the parabolic reflector includes cooling fins. An electric fan is used to speed up the passage of air and, thus, increase the cooling rate.
Direct cooling of a conventional lighting fixture using a fan is shown in U.S. Pat. No. 4,321,659, issued to E. Wheeler.
Convection air cooling of a compact, electric discharge lamp is shown in U.S. Pat. No. 4,503,360, issued to D. Bedel. Bedel includes two compartments: one for a light source, such as a low-pressure discharge lamp, and the other for an electrical circuit for energizing the lamp. Heat generated from the lamp is directed away from the electrical circuit compartment, preventing failure of electrical components.
A fan for drawing air past light filters along a tortuous air path is shown in U.S. Pat. No. 4,546,420, issued to D. Wheeler, et al. Another air-cooled light is seen in U.S. Pat. No. 4,586,117, issued to W. Collins, the inventor herein.
A cooling device for a xenon arc lamp is shown in U.S. Pat. No. 3,626,176, to T. Tsugami. The reflector mirror is cooled, and a double-wall construction of the light source casing incorporates water jackets. Cooling air supplied at the bottom of the casing is directed through inner and outer concentric, annular passages formed in a supply duct.
Use of a heat sink as a cooling system connected to a reflector or a high intensity lamp is shown in U.S. Pat. No. 3,936,686, issued to D. Moore.
Another air-cooled arc lamp as shown in U.S. Pat. No. 3,180,981, issued to H. Ulffers, et al. Ulffers utilizes moving air in the lamp housing and cooling fans to facilitate removal of heat radiation. Use of a heat sink in a high intensity lamp in place of air cooling is shown in U.S. Pat. No. 3,361,903, issued to R. Brown.
A spotlight movable in both a horizontal and vertical plane as a result of corresponding movements of a handle operably connected thereto is shown in U.S. Pat. No. 4,074,125, issued to R. Casalou.
The prior art does not disclose concurrent universal movement of a spot or search light about two axes. The visual patterns available by controlling the movements simultaneously of a light about two independent axes are likewise not shown in the prior art.
The prior art does not disclose cooling by the use of more than one fan and a heat exchanger, each fan associated with either the cathode electrode or the anode electrode of an arc lamp.